While prior research has demonstrated that Blockchain technology can be integrated into IoT environments to address the following issues with authorisation mechanisms such as single point of failure, access rights validation, data or policy tampering, lack of transparency, and accountability for granted resources, etc., however, these authorisation mechanisms have limitations that must be addressed in order to offer effective, secure, flexible, and dynamic authorisation of IoT devices by the use of prospective Blockchain features. For instance, the schemes [1]} [2]} [3]} solely rely on the Blockchain to store the expression of privileges to access resources in the form of transactions without fully utilising the Blockchain's capabilities, such as smart contracts. Moreover, to create and store predefined access rights on the Blockchain introduces issues with static access rights, such as in static authorisation schemes [4]} [5]} that are incapable of capturing the dynamic policies and coping with the dynamic nature of IoT networks, such as device mobility, behaviour patterns, the need to perform critical operations, device compromise and failure, and so on. Some methods rely on traditional access control models such as access control list (ACL) [6]} and RBAC [7]} [8]} [9]} [10]}, respectively, and each of which has its own set of limitations in terms of their inflexible nature, time consumption, error-prone and coarse-grained level. Further, the authorisation schemes based on CapBAC models [5]}
